In recent years, wireless mobile devices, such as cell phones, smart phones, laptops, and tablet computers are widely used. They are typically powered by power cells that are rechargeable (e.g., batteries). Such wireless mobile devices are usually provided with a wired charging mechanism, such as a wall plug, for transferring power to the battery. The wired charging connections have become increasingly smaller and fragile. Additionally, as the number of mobile devices commonly used by one person increases, and the constant use of the mobile devices on the go, availability of power outlets to charge the batteries has become limited and problematic.
Although they may offer other functions, such as data communication, docking stations also provide electrical connectivity for charging of a portable electronic device, such as a mobile device. A docking station typically has an electrical connector for electrical connection to a mating connector of the mobile device, for charge transfer and possibly for transfer of other signals. The connectors vary as between different types of mobile devices. Even for a type of device from one manufacturer, the connectors may vary between newer and older models, or the like. The connector in a docking station that is compatible with one device often is not compatible with another device, which limits the applicability of the docking station.
Recently developed mobile device accessories have included inductive chargers, offered as an alternative to corded battery chargers and docking stations with electrical connectors. Inductive chargers wirelessly provide electrical charge to chargeable devices, via a coil in the charger and a corresponding coil in the portable device. In some examples, the charger takes the form of a pad on which one or more such chargeable devices may rest while charging. Any device with a coil and a battery charging circuit that can be driven by alternating current signals from the coil may be able to work with the inductive charger. Such inductive charging accessories have several limitations. The charging range is very limited, usually restricting the distance between the mobile device and the charging pad to be no more than several millimeters, and, in some instances, require the accessory to be in physical contact with the docking station. These limitations often prevent the mobile devices from being used and restrict movement of the mobile devices while the battery is charging.
Hence a need exists for mobile device battery chargers that do not require a wired connection to the mobile device and are capable of wirelessly charging multiple devices over wider positional ranges, allowing greater freedom of positioning between the devices and the chargers and permitting ease of use of the devices while the batteries are wirelessly charging.